Geographic Variation Thirteen subspecies in 3 subspecies groups. Subspecific identification in field problematic due to slight differences and individual variation, but separation to group more likely. Lowland Pacific group includes guttatus (coastal southern Alaska to western British Columbia), nanus (southern Alaska islands), verecundus (Queen Charlotte Islands), vaccinius (coastal southwestern British Columbia and northwestern Washington), jewetti (northwestern. Washington to northwestern California), slevini (interior south-central Washington to west-central California), munroi (central British Columbia and western Alberta to northern Montana), and oromelus (interior southern British Columbia east to northwestern Montana and south to northeastern California). All with backs gray to brown and pale to dark, with little to no reddish aspect, and with richly-colored tails. Interior Western Montane group includes sequoiensis (Sierra Nevada of California), polionotus (eastern California east to northwestern Utah and Arizona), and auduboni (southeastern Washington east to southern Montana, south to southern Arizona and New Mexico and western Texas). All with pale, grayish brown backs and duller, less contrasting tails; the last subspecies having distinctive buff undertail coverts. Northern group includes faxoni (southern Northwest Territories south to southern Alberta, east to Newfoundland and Maryland) and euborius (central Alaska and northern British Columbia).

Status and Distribution Common. Breeding: typically in conifer-dominated forests, usually in areas of relatively little undergrowth; also in deciduous forests. Migration: medium- to long-distance migrant, with western montane breeders wintering farthest south (to southern Guatemala). Early migrant in spring, with southern Great Lakes peak ±25 April; arrival in farthest reaches of breeding range ±10 May, though with stragglers still in West in early June. Fall: western montane birds begin migration in early September, but faxoni and guttatus group peak in East ±15 October. Western subspecies winter in coastal states from Washington south to southern Guatemala; faxoni group winters in Southeast (from southern New Jersey south), a few to southern Midwest, south to northeastern Mexico. Vagrant: regular to Bering Sea islands in migration and to Bermuda fall through spring; accidental north to northern Alaska and Canada, Greenland, Greater Antilles, and Europe.

Population Apparently more adaptable than other brown thrushes; there has been little expressed concern.